Glycidol is a useful substance as a raw material for polyglycerol, (poly) glycerol esters and dihydroxypropylamine as well as perfumes and cosmetics, detergents, drugs, paints, UV curing agents for semiconductors, etc.
As a method for producing glycidol compounds, there is known the method in which an aryl alcohol is oxidized in the presence of an oxidizing agent (for example, refer to JP 2001-106680A and JP 57-52341A). In addition, there is known the method in which glycerol carbonate is subjected to decarboxylation under a catalyst-free condition or in the presence of a neutral salt such as sodium sulfate (for example, refer to U.S. Pat. No. 2,856,413 and JP 6-157509A).
On the other hand, it is also known that the glycerol carbonate is produced by not only a method using phosgene but also a method of subjecting dimethyl carbonate, ethylene carbonate, propylene carbonate or the like and glycerol to exchange reaction therebetween, a method of obtaining the glycerol carbonate from glycerol and urea, etc.
Among these methods, the method using glycerol and urea is considered to be industrially advantageous, because it allows the glycerol carbonate to be produced in a facilitated manner at low costs. In this method, although the reaction proceeds even under a catalyst-free condition, it is known that the glycerol carbonate is produced from glycerol and urea with a high yield when using a Lewis acid such as zinc sulfate and manganese sulfate as a catalyst in the reaction (for example, refer to EP 0955298A). Further, it is also known the method in which glycerol and urea are reacted in the presence of a dehydration agent (for example, refer to JP 2000-247967A).
However, in these conventionally known methods, since the decarboxylation reaction of glycerol carbonate is carried out at a temperature as high as about 200° C., undesirable side reactions such as reaction between molecules of chemically unstable glycidol and reaction between glycidol and glycerol carbonate as a raw material of the glycidol tend to be induced to thereby cause problems such as low yield of glycidol as the aimed product.
Further, the conventionally known methods for producing glycidol from glycerol carbonate (for example, those methods as described in U.S. Pat. No. 2,856,413 and JP 6-157509A) have almost failed to certainly specify suppression of the side reactions. Thus, there are not conventionally known the methods for producing glycidol from glycerol carbonate by decarboxylation reaction of the glycerol carbonate which can achieve the technical task of producing the glycidol with a high selectivity while suppressing occurrence of the side reactions.